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media/libvpx/vp9/common/vp9_treecoder.h@6474c204b198 (annotated)

media/libvpx/vp9/common/vp9_treecoder.h

Wed, 31 Dec 2014 06:09:35 +0100

author
Michael Schloh von Bennewitz <michael@schloh.com>
date
Wed, 31 Dec 2014 06:09:35 +0100
changeset 0
6474c204b198
permissions
-rw-r--r--

Cloned upstream origin tor-browser at tor-browser-31.3.0esr-4.5-1-build1
revision ID fc1c9ff7c1b2defdbc039f12214767608f46423f for hacking purpose.

michael@0 1 /*
michael@0 2 * Copyright (c) 2010 The WebM project authors. All Rights Reserved.
michael@0 3 *
michael@0 4 * Use of this source code is governed by a BSD-style license
michael@0 5 * that can be found in the LICENSE file in the root of the source
michael@0 6 * tree. An additional intellectual property rights grant can be found
michael@0 7 * in the file PATENTS. All contributing project authors may
michael@0 8 * be found in the AUTHORS file in the root of the source tree.
michael@0 9 */
michael@0 10
michael@0 11 #ifndef VP9_COMMON_VP9_TREECODER_H_
michael@0 12 #define VP9_COMMON_VP9_TREECODER_H_
michael@0 13
michael@0 14 #include "./vpx_config.h"
michael@0 15 #include "vpx/vpx_integer.h"
michael@0 16 #include "vp9/common/vp9_common.h"
michael@0 17
michael@0 18 typedef uint8_t vp9_prob;
michael@0 19
michael@0 20 #define vp9_prob_half ((vp9_prob) 128)
michael@0 21
michael@0 22 typedef int8_t vp9_tree_index;
michael@0 23
michael@0 24 #define TREE_SIZE(leaf_count) (2 * (leaf_count) - 2)
michael@0 25
michael@0 26 #define vp9_complement(x) (255 - x)
michael@0 27
michael@0 28 /* We build coding trees compactly in arrays.
michael@0 29 Each node of the tree is a pair of vp9_tree_indices.
michael@0 30 Array index often references a corresponding probability table.
michael@0 31 Index <= 0 means done encoding/decoding and value = -Index,
michael@0 32 Index > 0 means need another bit, specification at index.
michael@0 33 Nonnegative indices are always even; processing begins at node 0. */
michael@0 34
michael@0 35 typedef const vp9_tree_index vp9_tree[];
michael@0 36
michael@0 37 struct vp9_token {
michael@0 38 int value;
michael@0 39 int len;
michael@0 40 };
michael@0 41
michael@0 42 /* Construct encoding array from tree. */
michael@0 43
michael@0 44 void vp9_tokens_from_tree(struct vp9_token*, vp9_tree);
michael@0 45
michael@0 46 /* Convert array of token occurrence counts into a table of probabilities
michael@0 47 for the associated binary encoding tree. Also writes count of branches
michael@0 48 taken for each node on the tree; this facilitiates decisions as to
michael@0 49 probability updates. */
michael@0 50
michael@0 51 void vp9_tree_probs_from_distribution(vp9_tree tree,
michael@0 52 unsigned int branch_ct[ /* n - 1 */ ][2],
michael@0 53 const unsigned int num_events[ /* n */ ]);
michael@0 54
michael@0 55
michael@0 56 static INLINE vp9_prob clip_prob(int p) {
michael@0 57 return (p > 255) ? 255u : (p < 1) ? 1u : p;
michael@0 58 }
michael@0 59
michael@0 60 // int64 is not needed for normal frame level calculations.
michael@0 61 // However when outputing entropy stats accumulated over many frames
michael@0 62 // or even clips we can overflow int math.
michael@0 63 #ifdef ENTROPY_STATS
michael@0 64 static INLINE vp9_prob get_prob(int num, int den) {
michael@0 65 return (den == 0) ? 128u : clip_prob(((int64_t)num * 256 + (den >> 1)) / den);
michael@0 66 }
michael@0 67 #else
michael@0 68 static INLINE vp9_prob get_prob(int num, int den) {
michael@0 69 return (den == 0) ? 128u : clip_prob((num * 256 + (den >> 1)) / den);
michael@0 70 }
michael@0 71 #endif
michael@0 72
michael@0 73 static INLINE vp9_prob get_binary_prob(int n0, int n1) {
michael@0 74 return get_prob(n0, n0 + n1);
michael@0 75 }
michael@0 76
michael@0 77 /* this function assumes prob1 and prob2 are already within [1,255] range */
michael@0 78 static INLINE vp9_prob weighted_prob(int prob1, int prob2, int factor) {
michael@0 79 return ROUND_POWER_OF_TWO(prob1 * (256 - factor) + prob2 * factor, 8);
michael@0 80 }
michael@0 81
michael@0 82 static INLINE vp9_prob merge_probs(vp9_prob pre_prob,
michael@0 83 const unsigned int ct[2],
michael@0 84 unsigned int count_sat,
michael@0 85 unsigned int max_update_factor) {
michael@0 86 const vp9_prob prob = get_binary_prob(ct[0], ct[1]);
michael@0 87 const unsigned int count = MIN(ct[0] + ct[1], count_sat);
michael@0 88 const unsigned int factor = max_update_factor * count / count_sat;
michael@0 89 return weighted_prob(pre_prob, prob, factor);
michael@0 90 }
michael@0 91
michael@0 92 static unsigned int tree_merge_probs_impl(unsigned int i,
michael@0 93 const vp9_tree_index *tree,
michael@0 94 const vp9_prob *pre_probs,
michael@0 95 const unsigned int *counts,
michael@0 96 unsigned int count_sat,
michael@0 97 unsigned int max_update_factor,
michael@0 98 vp9_prob *probs) {
michael@0 99 const int l = tree[i];
michael@0 100 const unsigned int left_count = (l <= 0)
michael@0 101 ? counts[-l]
michael@0 102 : tree_merge_probs_impl(l, tree, pre_probs, counts,
michael@0 103 count_sat, max_update_factor, probs);
michael@0 104 const int r = tree[i + 1];
michael@0 105 const unsigned int right_count = (r <= 0)
michael@0 106 ? counts[-r]
michael@0 107 : tree_merge_probs_impl(r, tree, pre_probs, counts,
michael@0 108 count_sat, max_update_factor, probs);
michael@0 109 const unsigned int ct[2] = { left_count, right_count };
michael@0 110 probs[i >> 1] = merge_probs(pre_probs[i >> 1], ct,
michael@0 111 count_sat, max_update_factor);
michael@0 112 return left_count + right_count;
michael@0 113 }
michael@0 114
michael@0 115 static void tree_merge_probs(const vp9_tree_index *tree,
michael@0 116 const vp9_prob *pre_probs,
michael@0 117 const unsigned int *counts,
michael@0 118 unsigned int count_sat,
michael@0 119 unsigned int max_update_factor, vp9_prob *probs) {
michael@0 120 tree_merge_probs_impl(0, tree, pre_probs, counts,
michael@0 121 count_sat, max_update_factor, probs);
michael@0 122 }
michael@0 123
michael@0 124
michael@0 125 #endif // VP9_COMMON_VP9_TREECODER_H_

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